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Abstract:

A one-piece bearing is provided for use with a fluid processing assembly
of the type having an umbilicus, a bearing support, a gimbal received
within the bearing support, and a liner at least partially received
within the gimbal. The bearing is secured to a midsection of the
umbilicus and adapted to be at least partially received within the liner.
An inner surface of the bearing engages the umbilicus while an outer
surface of the bearing engages at least a portion of the liner for
rotation relative to the liner.

Claims:

1. A fluid processing assembly of the type having a bearing support and a
gimbal assembly received within the bearing support, the fluid processing
assembly comprising: an umbilicus having a first end and a second end;
and a one-piece thrust bearing secured to the umbilicus at a location
between the ends and adapted to be at least partially received within the
gimbal assembly, the bearing including an inner lumen through which the
umbilicus extends and an outer surface including a bearing surface
adapted to engage at least a portion of the gimbal assembly for rotation
relative to the gimbal assembly.

2. The fluid processing assembly of claim 1, wherein the bearing is
adapted to be temporarily secured to the gimbal assembly by longitudinal
relative movement of the bearing and/or the gimbal assembly toward each
other and the outer surface of the bearing includes a lead-in surface
adapted to contact a retaining member associated with the gimbal assembly
when the bearing is moved into the gimbal assembly and to pass beyond the
retaining member and into the gimbal assembly.

3. The fluid processing assembly of claim 2, wherein the lead-in surface
is adapted to automatically contact and move beyond the retaining member
and into the gimbal assembly during a fluid processing procedure.

4. The fluid processing assembly of claim 1, wherein the bearing is
adapted to be disassociated from the gimbal assembly by longitudinal
relative movement of the bearing and/or the gimbal assembly away from
each other and the outer surface of the bearing includes a lead-out
surface adapted to contact a retaining member associated with the gimbal
assembly when the bearing is moved out of the gimbal assembly and to pass
beyond the retaining member and out of the gimbal assembly.

5. The fluid processing assembly of claim 1, wherein the bearing is
adapted to be temporarily secured to the gimbal assembly by longitudinal
relative movement of the bearing and/or the gimbal assembly toward each
other and to be disassociated from the gimbal assembly by longitudinal
relative movement of the bearing and/or the gimbal assembly away from
each other and the outer surface of the bearing includes a lead-in
surface adapted to contact a retaining member associated with the gimbal
assembly when the bearing is moved into the gimbal assembly and to pass
beyond the retaining member and into the gimbal assembly and a lead-out
surface adapted to contact the retaining member when the bearing is moved
out of the gimbal assembly and to pass beyond the retaining member and
out of the gimbal assembly.

6. The fluid processing assembly of claim 5, wherein the lead-out surface
defines a greater angle to a central axis of the bearing than the lead-in
surface.

7. The fluid processing assembly of claim 1, wherein the bearing or a
portion of the gimbal assembly adapted to engage the bearing is
substantially comprised of polybutylene terephthalate; a combination
including polybutylene terephthalate and polytetrafluoroethylene; a
combination including polybutylene terephthalate and silicone oil or gum;
or a combination including polybutylene terephthalate,
polytetrafluoroethylene, and silicone oil or gum.

8. The fluid processing assembly of claim 1, wherein a portion of the
gimbal assembly adapted to engage the bearing is comprised of a material
including stainless steel with a polyether ether ketone coating.

9. The fluid processing assembly of claim 1, wherein the inner lumen of
the bearing includes a traction feature which bears against the umbilicus
to prevent relative rotation of the bearing and the umbilicus.

10. The fluid processing assembly of claim 1, wherein the bearing
includes a minor diameter portion adapted to contact the gimbal assembly
to maintain the bearing in substantially coaxial relationship thereto and
a major diameter portion adapted to contact the gimbal assembly to
transmit a substantially axial force therebetween.

11. The fluid processing assembly of claim 1, wherein the outer surface
of the bearing includes a generally hemispherical portion adapted to
contact the gimbal assembly.

12. A fluid processing assembly of the type having a bearing support and
a gimbal assembly received within the bearing support and having an inner
surface comprising an axially-extending wall generally coaxial with a
central axis of the gimbal assembly and a radially-extending wall
extending generally away from the central axis of the gimbal assembly,
the fluid processing assembly comprising: an umbilicus having a first end
and a second end; and a one-piece thrust bearing secured to the umbilicus
at a location between the ends and adapted to be at least partially
received within the gimbal assembly and comprising an inner lumen through
which the umbilicus extends and an outer surface adapted to engage at
least a portion of the gimbal assembly for rotation relative to the
gimbal assembly and comprising an axially-extending bearing surface
adapted to engage at least a portion of the axially-extending wall of the
gimbal assembly, and a radially-extending bearing surface adapted to
engage at least a portion of the radially-extending wall of the gimbal
assembly.

13. The fluid processing assembly of claim 12, further comprising a
retaining member associated with the gimbal assembly, wherein the bearing
is adapted to be temporarily secured to the gimbal assembly by
longitudinal relative movement of the bearing and/or the gimbal assembly
toward each other and the outer surface of the bearing includes a lead-in
surface adapted to contact the retaining member when the bearing is moved
into the gimbal assembly and to pass beyond the retaining member and into
the gimbal assembly.

14. The fluid processing assembly of claim 13, wherein the lead-in
surface is adapted to automatically contact and move beyond the retaining
member and into the gimbal assembly during a fluid processing procedure.

15. The fluid processing assembly of claim 12, further comprising a
retaining member associated with the gimbal assembly, wherein the bearing
is adapted to be disassociated from the gimbal assembly by longitudinal
relative movement of the bearing and/or the gimbal assembly away from
each other and the outer surface includes a lead-out surface adapted to
contact the retaining member when the bearing is moved out of the gimbal
assembly and to pass beyond the retaining member and out of the gimbal
assembly.

16. The fluid processing assembly of claim 12, further comprising a
retaining member associated with the gimbal assembly, wherein the bearing
is adapted to be temporarily secured to the gimbal assembly by
longitudinal relative movement of the bearing and/or the gimbal assembly
toward each other and to be disassociated from the gimbal assembly by
longitudinal relative movement of the bearing and/or the gimbal assembly
away from each other and the outer surface of the bearing includes a
lead-in surface adapted to contact the retaining member when the bearing
is moved into the gimbal assembly and to pass beyond the retaining member
and into the gimbal assembly and a lead-out surface adapted to contact
the retaining member when the bearing is moved out of the gimbal assembly
and to pass beyond the retaining member and out of the gimbal assembly.

17. The fluid processing assembly of claim 16, wherein the lead-out
surface defines a greater angle to a central axis of the bearing than the
lead-in surface.

18. The fluid processing assembly of claim 12, wherein the bearing or a
portion of the gimbal assembly adapted to engage the bearing is
substantially comprised of polybutylene terephthalate; a combination
including polybutylene terephthalate and polytetrafluoroethylene; a
combination including polybutylene terephthalate and silicone oil or gum;
or a combination including polybutylene terephthalate,
polytetrafluoroethylene, and silicone oil or gum.

19. The fluid processing assembly of claim 12, wherein a portion of the
gimbal assembly adapted to engage the bearing is comprised of a material
including stainless steel with a polyether ether ketone coating.

20. The fluid processing assembly of claim 12, wherein the inner surface
of the bearing includes a traction feature which bears against the
umbilicus to prevent relative rotation of the bearing and the umbilicus.

Description:

BACKGROUND

[0001] 1. Field of the Disclosure

[0002] The present subject matter relates to a bearing and bearing
assembly for supporting an umbilicus used, for example, in a fluid
processing system.

[0003] 2. Description of Related Art

[0004] Whole blood is routinely separated into its various components,
such as red blood cells, platelets, and plasma. In typical blood
processing systems, whole blood is drawn from a donor, the particular
blood component or constituent is removed and collected, and the
remaining blood constituents are returned to the donor. By thus removing
only particular constituents, less time is needed for the donor's body to
return to normal, and donations can be made at more frequent intervals
than when whole blood is collected. This increases the overall supply of
blood constituents, such as plasma and platelets, made available for
health care.

[0005] Whole blood is typically separated into its constituents through
centrifugation. This requires that the whole blood be passed through a
centrifuge after it is withdrawn from, and before it is returned to, the
donor. To avoid contamination, the blood is usually contained within a
sealed, sterile system during the entire centrifugation process. Typical
blood processing systems thus include a permanent, reusable centrifuge
assembly or "hardware" that spins and pumps the blood, and a disposable,
sealed and sterile fluid processing or fluid circuit assembly that
actually makes contact with the donor's blood. The centrifuge assembly
engages and spins a portion of the fluid processing assembly (often
called the centrifuge or separation chamber) during a collection
procedure. The blood, however, makes actual contact only with the fluid
processing assembly, which is used only once and then discarded.

[0006] To avoid the need for rotating seals, and to preserve the sterile
and sealed integrity of the fluid processing assembly, blood processing
systems often utilize centrifuges that operate on the "one-omega,
two-omega" operating principle. This principle is disclosed in detail in
U.S. Pat. No. 4,120,449 to Brown et al., which is hereby incorporated by
reference, and enables centrifuges to spin a sealed, closed system
without the need for rotating seals and without twisting the components
of the system. Blood processing systems that make use of the principle
typically include a fluid processing assembly that includes a plastic bag
or molded chamber that is spun in the centrifuge and that is connected to
the blood donor and to a stationary portion of the centrifuge assembly
through an elongated member that may be made up of one or more plastic
tubes. The elongated member is commonly referred to as an "umbilicus" and
is typically arranged in a question mark (or upside-down question mark)
configuration with both of its end portions coaxially aligned with the
axis of rotation of the centrifuge. The centrifuge chamber is rotated at
"two-omega" RPM and the umbilicus is orbited around the centrifuge
chamber at "one-omega" RPM. In other words, one end of the umbilicus is
stationary, the other end rotates at a two-omega speed with the
centrifuge chamber to which it is attached, and the intermediate portion
or midsection of the umbilicus orbits about the chamber at a one-omega
speed. The effect is that the end of the umbilicus, which is opposite the
bag or chamber and is connected to the donor via plastic tubing, does not
twist up as the bag is spun. The sealed, sterile integrity of the fluid
processing assembly is thus maintained without the need for rotating
seals.

[0007] U.S. Pat. Nos. 5,989,177 to West et al. and 6,344,020 to Reitz et
al., both of which are hereby incorporated herein by reference, disclose
one such blood processing apparatus based on the "one-omega, two-omega"
operating principle. In this apparatus, a disposable fluid processing
assembly having an umbilicus and a processing chamber is mountable within
a centrifuge assembly. One end of the umbilicus is held rotationally
stationary substantially coaxial with the axis of centrifugal rotation.
The other end of the umbilicus joins the processing chamber and rotates
with the processing chamber around the axis of centrifugation at the
two-omega speed, up to about 3,000 RPM. The mid-portion of the umbilicus
is supported by a wing plate that rotates around the axis of
centrifugation at the one-omega speed, up to about 1,500 RPM. A thrust
bearing mounted on the umbilicus permits the umbilicus to rotate relative
to the wing plate as the wing plate and the processing chamber turn at
different speeds. The thrust bearing slides into a one piece gimbal
mounted in a recess provided on the wing plate. The gimbal helps keep the
fluid processing assembly properly positioned during the centrifugation
procedure. When the procedure is completed, the thrust bearing can be
slid out of the gimbal in the wing plate to permit removal of the fluid
processing assembly.

[0008] Prior thrust bearings employ a plurality of ball bearings to
facilitate relative rotation between the umbilicus and wing plate. While
such systems have proven suitable, they require a number of precision
components to accommodate the ball bearings, and there remains a need for
an improved and preferably lower cost bearing or bearing assembly for
such processing systems, particularly that don't employ ball bearing
arrangements.

SUMMARY

[0009] There are several aspects of the present subject matter which may
be embodied separately or together in the devices and systems described
and claimed below. These aspects may be employed alone or in combination
with other aspects of the subject matter described herein, and the
description of these aspects together is not intended to preclude the use
of these aspects separately or the claiming of such aspects separately or
in different combinations as set forth in the claims appended hereto.

[0010] In one aspect, a fluid processing assembly of the type having a
bearing support and a gimbal assembly received within the bearing support
is provided. The fluid processing assembly further includes an umbilicus
having first and second ends and a one-piece thurst bearing secured to
the umbilicus at a location between the ends. The bearing is adapted to
be at least partially received within the gimbal assembly. The bearing
includes an inner lumen through which the umbilicus extends and an outer
surface adapted to engage at least a portion of the gimbal assembly for
rotation relative to the gimbal assembly.

[0011] In another aspect, a fluid processing assembly of the type having a
bearing support and a gimbal assembly received within the bearing support
is provided. The gimbal assembly is of the type having an inner surface
comprising an axially-extending wall generally coaxial with a central
axis of the gimbal assembly and a radially-extending wall extending
generally away from the central axis of the gimbal assembly. The fluid
processing assembly further includes an umbilicus having first and second
ends and a one-piece thrust bearing secured to the umbilicus at a
location between the ends. The bearing is adapted to be at least
partially received within the gimbal assembly and includes an inner lumen
through which the umbilicus extends and an outer surface adapted to
engage at least a portion of the gimbal assembly for rotation relative to
the gimbal assembly. The outer surface of the bearing comprises an
axially-extending bearing surface adapted to engage at least a portion of
the axially-extending wall of the gimbal assembly and a
radially-extending bearing surface adapted to engage at least a portion
of the radially-extending wall of the gimbal assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a perspective view of an exemplary durable fluid
processing system in which bearing assemblies according to the present
disclosure may be employed;

[0013] FIG. 2 is a perspective view of a disposable fluid processing or
fluid circuit assembly usable in association with the durable fluid
processing system of FIG. 1,

[0014] FIG. 3 is a side elevational view of the disposable fluid
processing assembly of FIG. 2 mounted on the durable fluid processing
system of FIG. 1, which is partially broken away;

[0015] FIG. 4 is a side detail view of a centrifuge included in the
durable fluid processing system of FIG. 1, showing the centrifuge in
combination with an umbilicus of the disposable fluid processing
assembly;

[0016] FIG. 5 is a perspective detail view of a bearing support of the
centrifuge of FIG. 4;

[0017] FIG. 6 is a perspective view of an umbilicus bearing assembly
according to an aspect of the present disclosure;

[0018] FIG. 7 is an exploded view of the umbilicus bearing assembly of
FIG. 6;

[0019] FIG. 8 is a perspective view of a gimbal of the umbilicus bearing
assembly of FIG. 6;

[0020] FIG. 9 is a perspective view of a liner that may be received within
and form a portion of the gimbal or gimbal assembly of the umbilicus
bearing assembly of FIG. 6;

[0021] FIG. 10 is a cross-sectional perspective view of the liner of FIG.
9;

[0022] FIG. 11 is a cross-sectional view of the umbilicus bearing assembly
of FIG. 6;

[0023] FIG. 12 is a perspective view of a portion of the gimbal, liner,
and retaining member of the umbilicus bearing assembly of FIG. 6;

[0024] FIG. 13 is a perspective view of the one-piece bearing of the
umbilicus bearing assembly of FIG. 6;

[0025] FIG. 14 is a front elevational view of the bearing of FIG. 13;

[0026] FIG. 15 is a cross-sectional perspective detail view of a retainer
portion of the bearing of FIG. 13 for engaging or gripping an umbilicus
(not shown) that extends through the bearing;

[0027] FIG. 16 is a perspective view of an alternative embodiment of a
one-piece bearing according to the present disclosure;

[0028] FIG. 17 is an exploded view of an alternative embodiment of a
one-piece bearing and gimbal liner according to the present disclosure;
and

[0029] FIG. 18 is a cross-sectional view of the bearing and liner of FIG.
17 mounted within a gimbal.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0030] The embodiments disclosed herein are for the purpose of providing
the required description of the present subject matter. They are only
exemplary, and may be embodied in various forms and in various
combinations. Therefore, specific details disclosed herein are not to be
interpreted as limiting the subject matter as defined in the accompanying
claims.

[0031] FIG. 1 shows a centrifugal fluid processing system 10 that may be
used in combination with an umbilicus bearing assembly according to the
present disclosure. The system is currently marketed as the AMICUS®
separator by Fenwal, Inc. of Lake Zurich, Ill. The system 10 can be used
for processing various fluids, but is particularly well suited for
processing whole blood, blood components, or other suspensions of
biological cellular materials. The system 10 includes a centrifuge
assembly 12 for separating a fluid into its constituent parts. A more
detailed description of the centrifuge assembly 12 and the other elements
of the system 10 can be found in U.S. Pat. No. 5,996,634, which is
incorporated by reference herein.

[0032] The durable fluid processing system 10 is used in combination with
a disposable processing set or fluid circuit 14, an example of which is
shown in FIG. 2. FIG. 3 shows the disposable set 14 mounted on the
durable system 10. The disposable set 14 is a preferably single use,
disposable item loaded on the system 10 at the time of use. After a fluid
processing procedure has been completed, the operator preferably removes
the disposable set 14 from the system 10 and discards it.

[0033] The disposable set 14 includes a processing chamber 16 (FIG. 2). In
use, the centrifuge assembly 12 rotates the processing chamber 16 to
centrifugally separate blood components. Whole blood is conveyed to the
processing chamber 16, and separated blood components are conveyed from
the processing chamber 16, through a plurality of flexible tubes that
form part of a fluid circuit 18. The fluid circuit 18 further includes a
plurality of containers 20 that may be supported by elevated hangers
located over the centrifuge assembly 12 (see FIG. 3) and that dispense
and receive liquids during processing. Fluid flow through the fluid
circuit 14 may be controlled in a variety of ways. Preferably, fluid flow
is controlled via cassettes 22 with pre-formed fluid passageways, which
may be selectively opened and closed pneumatically, hydraulically, or by
movable actuators. The number of cassettes may vary, but in the
illustrated embodiment, there are three cassettes 22, which operate in
association with valve and pump stations on the centrifuge assembly 12 to
direct liquid flow among multiple liquid sources and destinations during
a blood processing procedure. Tubes connected to the processing chamber
16 lead to a flexible umibicus 24, with additional tubes at the other end
of the umbilicus 24 fluidly connecting the processing chamber 16 (via the
umbilicus 24) to the remainder of the disposable set 14, including the
containers 20 and the cassettes 22. The umbilicus 24 will be described in
greater detail herein. Advantageously, the disposable set 14 is a
pre-assembled closed system, assuring an operator that it is a sterile
unit.

[0034] As illustrated, the centrifuge assembly 12 includes a wheeled
cabinet 26 that can be easily rolled from place to place. A user actuable
processing controller 30 is provided which enables the operator to
control various aspects of the blood processing procedure. A centrifuge
rotor assembly 32 is provided behind a fold open door 34 that can be
pulled open at the front of the cabinet 26 (FIG. 3). A plurality of valve
and pump stations 36 (FIG. 1) are provided on the top face of the cabinet
for receiving and controlling the various cassettes 22. A plurality of
hooks or hangers 38 are provided on the cabinet 26 for suspending the
various containers 20.

[0035] In use, the fold open door 34 is opened and the processing chamber
16 of the disposable set 14 is mounted in the centrifuge rotor assembly
32 (FIG. 4). The umbilicus 24 is threaded through the centrifuge rotor
assembly 32 and out through an opening 40 in the upper panel of the
cabinet 26 (FIG. 3). The cassettes 22 are snapped into respective ones of
the valve and pump stations 36 and the containers 20 are hung from the
appropriate hangers 38 (FIG. 3). After appropriate connections are made
to the donor using known intravenous techniques, the operator enters
appropriate commands on the processing controller 30 to begin the
processing procedure.

[0036] Looking more closely at the centrifuge rotor assembly 32 (FIG. 4),
it includes a chamber assembly 42 that is supported for rotation around
an axis of centrifugation 44. The centrifuge further includes a
centrifuge yoke assembly 46 that includes a yoke base 48, a pair of
upstanding yoke arms 50, and a yoke cross member 52 mounted between the
arms 50. The yoke base 48 is rotatably supported on a stationary platform
54 that carries the rotating mass of the centrifuge rotor assembly 32.
The yoke base 48 is also supported for rotation around the axis of
centrifugation independently of the chamber assembly 42. An electric
drive 56 rotates the yoke assembly 46 relative to the stationary platform
54 around the axis of centrifugation 44. The chamber assembly 42 is free
to rotate around the axis of centrifugation 44 at a rotational speed that
is different from the rotational speed of the yoke assembly 46.

[0037] Referring further to FIG. 4, the chamber assembly 42 defines an
annular chamber 58, centered around the axis of centrifugation 44, for
receiving the processing chamber 16 of the disposable set 14. The
umbilicus 24 extends through the lower center of the chamber assembly 42
in alignment with the axis of centrifugation 44. A first anchor portion
60 integrally molded or otherwise mounted onto the umbilicus 24, is
received in a lowermost umbilicus mount 62 located at the lower center of
the chamber assembly 42. The first anchor portion 60 and umbilicus mount
62 function to transfer torque between the umbilicus 24 and chamber
assembly 42 so that the chamber assembly 42 rotates around the axis of
centrifugation in response to twisting of the umbilicus 24 around its
axis.

[0038] The other end of the umbilicus 24 is supported by means of a second
anchor portion 64 that is removably received in an upper umbilicus mount
66 positioned over the centrifuge chamber assembly 42 substantially in
alignment with the axis of centrifugation 44. An over-center clamp 68 at
the end of the upper umbilicus mount 66 clamps onto the second anchor
portion 64 to hold the adjacent segment of the umbilicus 24 rotationally
stationary and in collinear alignment with the axis of centrifugation 44.
The second anchor portion 64 may be integrally molded or otherwise
securely joined with the umbilicus 24.

[0039] As further illustrated in FIG. 4, the portion of the umbilicus 24
between the second anchor portion 64 and the first anchor portion 60 is
supported by a middle umbilicus mount or bearing support 70 (illustrated
in greater detail in FIG. 5) that is carried at the lower end of a wing
plate 72 extending outwardly and downwardly from the yoke cross member
52. As the electric drive 56 rotates the centrifuge yoke assembly 46
(FIG. 3) around the axis of centrifugation 44, the wing plate 72 and the
bearing support 70 pull the midsection of the umbilicus 24 around the
axis of centrifugation 44 as well. As the umbilicus 24 orbits around the
axis 44, at rotational speed one-omega, a twisting action is imparted to
the umbilicus 24 around its own axis. The midsection of the umbilicus 24
is free to rotate around its own axis relative to the wing plate 72 as
the yoke assembly 46 is turned, so it will tend to "untwist" against the
twisting motion imparted by the rotating yoke assembly 46. As it untwists
in this manner, the umbilicus 24 spins the centrifuge chamber assembly 42
around the axis of centrifugation 44 at an average rotational speed of
two-omega.

[0040] To maintain balance as the yoke assembly 46 turns, an additional
wing plate 74 extends from the yoke cross member 52 diametrically
opposite the wing plate 72. A counterweight 76 sufficient to balance the
mass of the bearing support 70 and umbilicus 24 is carried on the lower
end of the additional wing plate 74.

[0041] In accordance with one aspect of the present disclosure, the
midsection of the umbilicus 24 is supported on the wing plate 72 by means
of an umbilicus bearing assembly 78, which is shown in greater detail in
FIGS. 6 and 7. The illustrated umbilicus bearing assembly 78 includes, as
illustrated, several distinct parts, one or more of which could be
provided as integral combinations with other parts. Specifically, the
illustrated assembly includes a gimbal or liner receptacle 80, a liner or
bearing receptacle 82 at least partially received within the gimbal 80, a
one-piece bearing 84 at least partially received within the liner 82, and
a retaining member 86 which secures the bearing 84 within the liner 82.
Additionally, fasteners 88 may be provided to secure the gimbal 80 to the
liner 82 and a clip 90 in the form of a compression band or other
suitable structure may be provided to secure the bearing 84 to the
umbilicus 24.

[0042] The gimbal 80 of the umbilicus bearing assembly 78 is received
within the bearing support 70, which is shown in greater detail in FIG.
5. The bearing support 70 comprises a circular opening 92 formed in the
lowermost end of the wing plate 72. In the illustrated embodiment, the
sidewall 94 of the circular opening 92 is concavely shaped, thereby
giving the opening 92 a generally spherical shape. A gap 96 is formed in
the end of the wing plate 72 and opens into the circular opening 92 to
enable the umbilicus 24 and the umbilicus bearing assembly 78 to be
inserted into the opening 92 from the side. A pair of orthogonally
oriented pivot pins 98 extend from the sidewall 94 of the circular
opening 92 towards its center.

[0043] The gimbal 80 (FIG. 8) comprises a "C-shaped" member having a
generally annular or ring-like form. The outer surface 100 of the
illustrated gimbal 80 is outwardly rounded or convex, thereby giving the
gimbal 80 a generally spherical shape that matches the shape of the
opening 92 of the bearing support 70. A pair of elongated slots 102 (only
one of which is visible) are formed through the outer surface 100 and are
positioned and dimensioned to receive the pivot pins 98 when the gimbal
80 is received in the circular opening 92. The rounded outer surface 100
of the gimbal 80, together with the slots 102 and pivot pins 98 received
therein, enable the gimbal 80 to pivot within the circular opening 92
around two orthogonal axes. Such freedom of movement is referred to
herein as a "gimbaling" action or motion. A gap 104 is formed through the
side of the gimbal 80 to permit entry of the umbilicus 24. In one
embodiment, the gimbal 80 is formed of a durable, rigid, low-friction
plastic such as a Delrin® and/or polytetrafluoroethylene ("PTFE" or
Teflon®). While such material is sufficiently rigid to prevent
excessive wear during repeated use (the gimbal 80 being considered a part
of the durable fluid processing system 10 and not the disposable set 14),
it can be slightly flexed by pinching or squeezing (on account of the
thickness of the gimbal wall and the presence of the gap 104) so as to be
pressed into the circular opening 92 of the bearing support 70.

[0044] Similar to the gimbal 80, the liner or bearing receptacle 82 (FIGS.
9 and 10) comprises a generally "C-shaped" structure with a gap 106
opening through its side to permit passage of the umbilicus 24 during
installation. As with the gimbal 80, the liner 82 is a reusable component
of the umbilicus bearing assembly 78 which is intended for repeated use
as part of the durable fluid processing system 10. Although shown as a
separate part, the liner 82 could be integral and of one-piece
construction with the gimbal 80. The combination of the gimbal 80 and
liner 82 (whether provided separately or integrally) is referred to
herein as a gimbal assembly.

[0045] The liner 82 is configured to be at least partially received within
the gimbal 80 (FIG. 11). In the illustrated embodiment, a top surface 108
of the liner 82 abuts an upper ledge or transverse wall 110 of the gimbal
80 when the liner 82 is properly positioned within the gimbal 80, thereby
providing tactile feedback and a positive stop during assembly. The liner
82 may also include an upper rim 112 which simultaneously abuts a lower
ledge or transverse wall 114 of the gimbal 80 when the liner 82 is
properly positioned within the gimbal 80. Both the gimbal 80 and the
liner 82 include one or more apertures 116, with each aperture 116 of the
gimbal 80 being aligned with a corresponding aperture 116 of the liner 82
when the gap 104 of the gimbal 80 is aligned with the gap 106 of the
liner 82. The apertures 116 so aligned each accommodates a fastener 88
(such as the threaded screws shown in FIGS. 6 and 7) to secure the liner
82 within the gimbal 80. The liner 82 may be secured to the gimbal 80
either before or after the gimbal 80 is installed within the circular
opening 92 of the bearing support 70, though it may be advantageous to
first install the gimbal 80 so that it is not necessary to squeeze both
the gimbal 80 and the liner 82 upon installation of the gimbal 80 into
the circular opening 92. It may be advantageous for there to be some
amount of lateral clearance between the outer surface 120 of the liner 82
and the inner surface 122 of the gimbal 80. Such a space exposes the
outer surface 120 of the liner 82 to the air within the centrifuge 32,
thereby potentially reducing the temperature of the liner 82, which may
tend to heat up during fluid processing as a result of friction, as will
be described in greater detail herein.

[0046] The illustrated liner 82 further includes an upper section 124 with
a relatively small, substantially constant inner diameter (the surface of
which is referred to herein as an axially-extending wall 126) and a lower
section 128 with a relatively large, substantially constant inner
diameter (FIG. 10). The transition between the upper section 124 and the
lower section 18 is defined by a shoulder or radially-extending liner
wall 130, which may extend substantially radially or at a selected angle
or incline relative to the center axis. The opening defined by the upper
section 124 of the liner 82 is adapted to receive a minor diameter
portion 132 of the bearing 84, while the opening defined by the lower
section 128 of the liner 82 is adapted to received a major diameter
portion 134 of the bearing 84, as shown in FIG. 11. The shoulder 130 of
the liner 82 abuts a mating bearing surface 136 of the bearing 84 to
limit the degree to which the bearing 84 may be inserted into the liner
82 and to provide an arrangement that allows relative rotation between
the bearing 84 and the liner 82, while limiting axial movement as a
thrust bearing. Such a configuration of the inner surface of the liner 82
is adapted for use with the bearing 84 illustrated in FIGS. 7 and 11 and
it should be understood that a different configuration for the liner
inner surface may be more appropriate when the bearing configuration is
different.

[0047] The liner 82 of FIGS. 9-11 also includes a generally "U-shaped"
perimeter slot or channel or groove 138, which is defined between the
upper rim 112 and a lower rim 140 adjacent to a bottom end of the liner
82. The channel 138 receives the retaining member 86, as shown in FIGS.
11 and 12. The illustrated retaining member 86 includes an arcuate
crossbeam or cross member 142 (having a curvature substantially the same
as the curvature of the channel 138) and a pair of substantially parallel
legs 144 extending from the ends of the cross member 142. As shown in
FIG. 12, the cross member 142 is positioned diametrically opposite the
gap 106 of the liner 82, with the legs 144 extending from the cross
member 142 in the direction of the gap 106. Two opposing lateral passages
146 (best shown in FIGS. 9 and 10) extend through the wall of the liner
82, allowing a portion of each leg 144 of the retaining member 86 to
communicate with the open interior of the liner 82 (FIGS. 11 and 12). The
major diameter portion 134 of the bearing 84 is wider than the separation
between the legs 144 (FIG. 11), but the legs 144 are resilient (being
made of a material such as stainless steel or spring steel or the like),
thereby allowing the major diameter portion 134 of the bearing 84 to
press the legs 144 away from each other as the bearing 84 is pressed into
the liner 82. When the major diameter portion 134 has passed beyond the
legs 144 and into the liner 82, the legs 144 will resiliently return to
their original straight configuration (FIGS. 11 and 12), thereby
temporarily securing the bearing 84 within the liner 82. Such a
configuration provides a tactile and audible indication that the bearing
84 has been successfully loaded into the liner 82.

[0048] In one embodiment, the liner 82 is formed of a durable, high
stiffness material such as stainless steel. A metallic material may be
advantageous for drawing away from the bearing 84 any heat arising from
friction generated between the liner 82 and the bearing 84 during fluid
processing. Stainless steel may be particularly advantageous due to its
low corrosion nature and ability to accept a wide range of coatings for
further reducing friction between the interior of the liner 82 and the
exterior of the bearing 84. Among such low-friction coatings are
polyether ether ketone ("PEEK"), diamond-chrome, and nickel-boron
nitride. A PEEK coating may be advantageous because of its low
coefficient of friction, durability, and ability to withstand high
temperatures. Hence, it may be most advantageous to provide the liner 82
as a stainless steel component having an inner surface which is at least
partially coated with PEEK. However, other materials, including solid
polymers, may also be used without departing from the scope of the
present disclosure.

[0049] The one-piece bearing 84 (FIGS. 13 and 14) is generally tubular,
with an inner lumen or surface 148 defining an open interior sufficiently
sized to accommodate the umbilicus 24. During assembly of the disposable
set 14, the bearing 84 is slid axially or longitudinally onto and along
the umbilicus 24 to a position between the anchor portions 60, 64. The
bearing 84 is slid into place before one or both of the anchor portions
60, 64 is associated with the umbilicus 24, otherwise the presence of the
anchor portions 60, 64 would prevent proper positioning of the bearing
84. The bearing 84 is oriented with its minor diameter portion 132 facing
the upper anchor portion 64 and an attachment portion or flange portion
150 facing the lower anchor portion 60. The location of the bearing 84 on
the umbilicus 24 is referred to herein as a midsection of the umbilicus
24, although the bearing 84 is not necessarily located at the midpoint
between the upper and lower anchor portions 64 and 60.

[0050] It may be advantageous for the inner diameter of the bearing 84 to
be substantially the same as the outer diameter of the umbilicus 24 to
ensure that the umbilicus 24 fits snugly around the bearing 84, thereby
preventing radial or lateral movement of the umbilicus 24 within the
bearing 84. It may also be advantageous for one end of the inner lumen
148 of the bearing 84 (illustrated in FIG. 11 as the top end) to be
outwardly tapered to help guide the umbilicus 24 into the bearing 84
during assembly. Additionally, as the umbilicus 24 will tend to bend in
the region of the bearing support 70 during fluid processing, such a
taper provides a smooth surface to interface with a bending umbilicus 24,
thereby reducing stress and easing the shear forces experienced by the
bending umbilicus 24 at that location.

[0051] The inner lumen 148 of the bearing 84 is held in place against the
umbilicus 24 by any of a number of acceptable means, including an
adhesive or other bonding agent and/or a physical restraint. In the
embodiment illustrated in FIGS. 6 and 7, the bearing 84 is secured to the
umbilicus 24 by means of a compression band or clip 90 (FIGS. 6 and 7).
More particularly, the flange portion 150 of the bearing 84 (illustrated
as a bottom end of the bearing 84 in FIGS. 13 and 14) includes a
plurality of spaced-apart flanges or tabs 152 which can be forced
radially inwardly toward a central axis of the bearing 84. Each flange
152 has an indentation 154 on its outer surface, which indentations 154
align to form an annular seat for the clip 90. The clip 90 has a smaller
inner diameter than the lower end of the bearing 84, so when it is pushed
into contact with the lower end of the bearing 84 (upwardly in the
orientation of FIG. 7), it will force the flanges 152 radially inwardly,
eventually seating within the indentations 154. The flanges 152 will grip
the umbilicus 24, thereby preventing the bearing 84 from moving with
respect to the umbilicus 24. The inner surfaces of the flanges 152 may
include additional features to promote a secure grip by increasing the
force required to cause the bearing 84 to slip axially along the
umbilicus 24. For example, FIG. 15 shows one embodiment wherein the inner
surface of each flange 152 includes a traction feature comprised of a
plurality of parallel projections or barbs 156 which are oriented
transverse to the central axis of the bearing 84. In another embodiment,
shown in FIG. 16, the inner surface of each flange 152 includes a
traction member comprising a single "U-shaped" barb 158. Other barb
configurations may also be employed without departing from the scope of
the present disclosure. Other surface treatments could also be used to
enhance friction between the bearing 84 and umbilicus 24.

[0052] Turning now to the outer surface of the one-piece bearing 84, the
illustrated embodiment is comprised of three sections--the minor diameter
portion 132, the above-described flange or attachment portion 150, and
the major diameter portion 134, which is positioned between the minor
diameter portion 132 and the flange portion 150. The transition from the
minor diameter portion 132 to the major diameter portion 134 is defined
by the radially-extending bearing surface 136, which acts as a thrust
bearing in an axial direction and will be described in greater detail
herein. The transition from the major diameter portion 134 to the flange
portion 150 is defined by a lead-out surface 160 which will be described
in greater detail herein.

[0053] The minor diameter portion 132 is substantially tubular, with an
outer surface 162 configured to be received within the opening defined by
the axially-extending wall 126 of the liner 82 (FIG. 11). The outer
surface 162 of the minor diameter portion 132 is referred to herein as an
axially-extending bearing surface and is acted on by radial forces, as
will be described in greater detail herein. In the illustrated
embodiment, the diameter of the axially-extending bearing surface 162,
while being smaller than the diameter of the axially-extending liner wall
126, is comparable to the diameter of the axially-extending liner wall
126. Such a configuration has a number of benefits. For example, it
prevents the axially-extending bearing surface 162 from binding within
the axially-extending liner wall 126. At the same time, the diameters of
the axially-extending liner wall 126 and axially-extending bearing
surface 162 are sufficiently close that the axially-extending bearing
surface 162 is only allowed a small amount of lateral travel before
coming into contact with the axially-extending liner wall 126. This
ensures that the bearing 84 remains generally coaxial with the liner 82
during fluid processing for optimal performance.

[0054] As for the illustrated major diameter portion 134, it is comprised
of the radially-extending bearing surface 136, a lead-in surface 164, and
the lead-out surface 160. The illustrated radially-extending bearing
surface 136 extends from the axially-extending bearing surface 162 in a
direction generally away from the central axis of the bearing 84. in use,
the radially-extending bearing surface 136 abuts the shoulder 130 of the
liner 82 (FIG. 11), with the two being oriented at approximately the same
angle to maximize the surface contact therebetween. Such a configuration
has a number of benefits. For one, it gives the bearing 84 a
self-centering feature with respect to the liner 82. Further, during use
the liner 82 presses against the bearing 84 with an axial force, but an
inclined interface therebetween gives the force a radial component, which
effectively reduces the magnitude of the force in the axial direction. In
the illustrated embodiment, the shoulder 130 and radially-extending
bearing surface 136 are inclined and oriented approximately 10°
from horizontal, sloping away from the associated axially-extending liner
wall 126 and axially-extending bearing surface 162, respectively. While
the illustrated angle for the radially-extending bearing surface 136 and
the shoulder 130 has been found to be advantageous, other configurations
and angles may also be employed without departing from the scope of the
present disclosure.

[0055] The illustrated lead-in surface 164 extends from an outer end of
the radially-extending bearing surface 136 and extends radially outwardly
therefrom. As shown in FIG. 11, the lead-in surface 164 is oriented at a
sharper incline than the radially-extending bearing surface 136. As best
illustrated in FIG. 11, the maximum diameter of the radially-extending
bearing surface 136 is approximately equal to or slightly smaller than
the separation between the legs 144 of the retaining member 86. Thus,
upon pressing the bearing 84 into the liner 82, the radially-extending
bearing surface 136 will pass into the liner 82 without contacting the
legs 144 of the retaining member 86. The lead-in surface 164, however, is
wider than the separation between the legs 144, so it will contact the
legs 144 as the bearing 84 is pressed into the liner 82. Rather than
getting caught upon the legs 144, the incline of the lead-in surface 164
gradually presses the legs 144 away from each other and allows the
lead-in surface 164 to pass beyond the legs 144 and into the liner 82.

[0056] The inclination of the lead-in surface 164 may be varied to
determine the force required to press the bearing 84 into the liner 82,
with greater inclination (i.e., closer to parallel with the central axis
of the bearing 84) tending to allow the bearing 84 to be loaded into the
liner 82 at a lower insertion force. For example, in one embodiment the
inclination of the lead-in surface 164 is approximately 15° from
parallel with the central axis of the bearing 84. Such an inclination is
sufficiently great that the bearing 84 can be automatically loaded into
the liner 82 upon rotation of the umbilicus 24 as part of a fluid
processing procedure. It should be noted that, while reference is made to
the lead-in surface 164 having an inclination, its configuration is not
limited to a strict frusto-conical shape with a uniform inclination. In
particular, the illustrated embodiment has a lead-in surface 164 which is
slightly parabolic or defined by a compound angle. Other configurations
of the lead-in surface 164 may also be employed without departing from
the scope of the present disclosure.

[0057] The outer edge of the lead-in surface 164 marks the transition
between the lead-in surface 164 and the lead-out surface 160. In contrast
to the lead-in surface 164, the lead-out surface 160 is inwardly inclined
or tapered (i.e., having an outer diameter which decreases as the bearing
84 is inserted into the liner 82). When the lead-in surface 164 has fully
passed beyond the legs 144 of the retaining member 86 and the outer
diameter of the bearing 84 begins to decrease (i.e., in the region of the
lead-out surface 160), the legs 144 begin to resiliently return to their
original straight configuration, pressing toward each other and against
the lead-out surface 160. At this point, the bearing 84 is temporarily
secured within the liner 82, as the lead-out surface 160 cannot exit the
liner 82 without being pulled (to press the legs 144 of the retaining
member 86 far enough apart from each other so as to allow passage of the
lead-out surface 160).

[0058] In the illustrated embodiment, the lead-out surface 160 defines a
greater angle to the central axis of the bearing 84 than the lead-in
surface 164, meaning that it will be easier to insert the bearing 84 into
the liner 82 than to remove the bearing 84 from the liner 82. For
example, in one embodiment, the lead-in surface 164 is inclined at
approximately 15° (from parallel with the central axis of the
bearing 84), while the lead-out surface 160 is inlined at approximately
45°. Such a configuration for the lead-out surface 160 may be
advantageous, as it causes the legs 144 of the retaining member 86 to
quickly "snap" back toward their original straight configuration,
providing a tactile and audible indication that the bearing 84 has been
successfully loaded into the liner 82. Also in the illustrated
embodiment, the lead-out surface 160 is tapered to a small enough outer
diameter that the legs 144 of the retaining member 86 will be returned to
their original straight configuration when the bearing 84 has been loaded
within the liner 82 (FIG. 11). This may be advantageous for a number of
reasons (including improving the durability of the retaining member 86),
but in other embodiments the lead-out surface 160 may only allow for a
partial return of the legs 144 of the retaining member 86 to their
original straight configuration upon full insertion of the bearing 84
into the liner 82.

[0059] The function of an umbilicus bearing assembly is to associate the
umbilicus to the bearing support while allowing the umbilicus to rotate
about its own central axis in the region of the bearing support. In
contrast to known umbilicus bearing assemblies which employ ball bearings
to permit rotation of the bearing (and, hence, the umbilicus) with
respect to the liner, the one-piece bearing 84 of the present disclosure
(particularly the radially-extending bearing surface 136 and the
axially-extending bearing surface 162) effectively slides against the
liner 82 for relative rotation. Accordingly, it is advantageous for the
bearing 84 to be comprised of a material having a low coefficient of
friction, thereby minimizing the amount of heat generated during use
while also ensuring that the umbilicus 24 is free to rotate about its own
central axis (as any binding of the bearing 84 within the liner 82 can
cause undesirable torsion of the umbilicus 24 during fluid processing).
Additional material characteristics of the bearing 84 may also be
advantageous. For example, it may be advantageous for the material used
to be resistant to abrasion and sufficiently rigid or hard so as to
withstand (without deformation) the forces exerted upon the bearing 84
during fluid processing. Another advantageous characteristic is a high
melt temperature, which prevents wear and softening of the bearing 84
upon reaching the maximum temperature and load during fluid processing.
Typically, the disposable set 14 (including the bearing 84) is sterilized
prior to use by way of an electron-beam or gamma sterilization process,
in which case it would be advantageous for the bearing material to be
able to withstand such a sterilization process without excessive
degradation.

[0060] Generally speaking, it has been found that a material having a
relatively high density will be suitable for use in forming the one-piece
bearing 84. More particularly, it has been found that selected polyesters
(especially reinforced polyesters) have the desired mechanical
characteristics and would perform suitably. Within the family of
reinforced polyesters, thermoplastic crystalline polymers may perform
particularly well due to their high formability with minimal shrinkage,
greater dimensional accuracy and endurance, high rigidity and mechanical
strength, high heat stability, and very low electrical conductivity (to
minimize the potential for static energy build up during rotation of the
umbilicus 24). In one embodiment, the bearing 84 is injection molded as a
single piece using the thermoplastic crystalline polymer polybutylene
terephthalate (PBT). It may be advantageous for the polymer base material
to include an additive to raise the flexural modulus and heat resistance
and to provide increased lubricity. When using a PBT base material,
suitable fillers include (but are not limited to) one or more of: aramid
fiber, PTFE/Teflon®, silicone oil or gum, and PEEK. These fillers
could work well in varying concentrations to produce the desired results,
including ease in injection moldability and high stiffness. In one
exemplary formulation, the bearing material is comprised of approximately
80% PBT, 18% PTFE, and 2% silicone oil or gum.

[0061] Alternatively, the material composition of the liner 82 and the
bearing 84 may be reversed. For example, the liner 82 may be a molded
component comprised of a polymeric material, such as a PBT base material
with a filler material (e.g., PTFE and/or silicone oil or gum), while the
bearing 84 may be comprised of a metallic material, such as stainless
steel with a PEEK coating.

[0062] An alternative embodiment of a bearing 166 and associated liner 168
according to the present disclosure is shown in FIG. 17, with FIG. 18
showing the bearing 166 and liner 168 being mounted within a gimbal 80
according to the foregoing description. The bearing 166 of FIG. 17 is
substantially the same as the bearing 84 of FIGS. 13 and 14, except for a
different major diameter portion 170. Rather than having a
radially-extending bearing surface 136, lead-in surface 164, and lead-out
surface 160, the major diameter portion 170 of the bearing 166 of FIG. 17
has a generally hemispherical outer surface. To accommodate such a
bearing 166, the inner surface 172 of the liner 168 defines a generally
conical or paraboloid open interior (FIG. 18). As in the previous
embodiment, the outer surface of the bearing 166 (particularly the major
diameter portion 170) directly engages the inner surface 172 of the liner
168 and effectively slides against the liner 168 for relative rotation.

[0063] The embodiment of FIGS. 17 and 18 also differs from the previous
embodiment in that it omits a retaining member or other means for
temporarily securing the bearing 166 within the liner 168. As described
previously, bearings according to the present disclosure may have a
self-loading function and the bearing, once loaded (whether manually or
automatically), will remain in the liner during fluid processing due to
the motion of the umbilicus 24, the forces exerted upon the umbilicus 24,
and the simple configuration of the bearing and liner. Accordingly, while
a retaining member provides additional security and assurance that the
bearing is properly loaded in the liner, it is not required. Hence, it
should be understood that the embodiment of FIGS. 6 and 7 may be
practiced without the retaining member 86 and that the embodiment of
FIGS. 17 and 18 may be practiced with a retaining means.

[0064] Prior to an operator beginning a fluid processing procedure, the
gimbal 80 and liner 82, 168 (being part of the durable fluid processing
system 10) are already in place within the bearing support 70 and the
bearing 84, 166 is already secured to the midsection of the umbilicus 24
at the appropriate location. The operator associates the various
components of the disposable set 14 with the corresponding components of
the fluid processing system 10 (e.g., hanging the containers 20 on the
designated hangers 38 and inserting each cassette 22 into the appropriate
valve and pump station 36). The user folds open the door 34 to gain
access to the centrifuge rotor assembly 32 (FIGS. 3 and 4). The user
places the processing chamber 16 in the annular chamber 58 and clamps the
anchor portions 60 and 64 of the umbilicus 24 into their designated
mounts 62 and 66. The umbilicus 24 is inserted sideways through the
aligned gaps 96, 104, and 106 of the bearing support 70, gimbal 80, and
liner 82, 168, with the bearing 84, 166 being positioned on the liner
side of the bearing support 70 (as opposed to the gimbal side of the
bearing support 70). The bearing 84, 166 can then be either pressed into
the liner 82, 168 or left in place to allow for an automatic loading
during fluid processing.

[0065] One the disposable set 14 is in place, the operator may proceed in
carrying out a fluid processing procedure (inputting instructions into
the controller 30, phlebotomizing a subject, etc.) according to known
methods.

[0066] It will be understood that the embodiments described above are
illustrative of some of the applications of the principles of the present
subject matter. Numerous modifications may be made by those skilled in
the art without departing from the spirit and scope of the claimed
subject matter, including those combinations of features that are
individually disclosed or claimed herein. For these reasons, the scope
hereof is not limited to the above description but is as set forth in the
following claims, and it is understood that claims may be directed to the
one-piece bearing alone, multiple components of the umbilicus bearing
assembly, one or more components of the umbilicus bearing assembly in a
larger fluid processing assembly, and/or methods for manufacturing,
loading, and/or using the same.

Patent applications by Mark B. Jones, Libertyville, IL US

Patent applications by Richard L. West, Lake Villa, IL US

Patent applications by Salvatore Manzella, Jr., Barrington, IL US

Patent applications in class Constituent removed from blood and remainder returned to body

Patent applications in all subclasses Constituent removed from blood and remainder returned to body